Fruit Removal Research Articles

A Semi-Automated Harvesting Prototype for Shaking Fruit Tree Limbs

Mechanizing the fruit removal operation during fresh-market apple harvesting is essential for labor and cost savings for fruit growers. This study introduces a semi-automated mechanical fruit harvesting system that uses a fruit removal technique based a unique limb shaking mechanism called a dual motor actuator (DMA). The harvesting system was tested on ‘Gala‘ apples grown in a formally trained fruiting wall orchard. A manipulator arm, positioned by a human, held a fruit catchframe and an end-effector. The system was mounted on a mobile orchard platform. The DMA was developed as an infinitely variable pattern end-effector that applies rhythmic motions to a fruiting limb to remove fruit. The novelty of the DMA design is the use of two eccentrics mounted to electric motors that are pinned together to form a triangle with an adjustable base. Pattern, rhythm, and actuation time were varied to characterize the removal efficiency and fruit damage percentages. Removal efficiency averaged only 35% across the fruiting limb but increased to 88% within the actuation zone of the fruiting section, showing the potential of a semi-selective harvesting technique for localized fruit removal on branches trained to trellis wires. A circular pattern using a 200 cycles min-1 rhythm achieved the lowest overall damage (10%) of all combinations of the patterns and rhythms tested. Bruise percentage was also lowest (4%) using the same pattern and rhythm. Rhythm and actuation time were significant factors that influenced the fruit removal condition. No fruit was removed outside of the targeted actuation zone when using a single limb grasper. This localized limb actuation method shows great potential for removing apples from a limb while maintaining fresh-market quality fruit.

AVG application regimes play an important role on pre-harvest drop and ripening of ‘Jonagold’ apples

This study was carried out to investigate the effects of different AVG (aminoethoxyvinylglycine) treatments on pre-harvest fruit drop rates and ripening levels of ‘Jonagold’ apples. A total of 225 mg L-1 AVG dose was applied at once in a single application at different times or divided into doses and applied different times. Compared to control treatment, entire AVG treatments increased fruit removal force and significantly decreased the pre-harvest drop rates. AVG treatments applied at once (225 mg L-1) 8 or 4 weeks before the anticipated harvest time were found to be more effective than the divided treatments. AVG treatments inhibited ethylene biosynthesis and such an inhibition was more distinctive in single 225 mg L-1 treatments. AVG treatments decreased flesh softening, starch degradation rates and consequently retarded fruit ripening. The 225 mg L-1 AVG treatment applied 4 weeks before the harvest significantly increased L* value and hue angle both in the year 2010 and 2011. NAA (naphtaleneacetic acid) at 10 mg L-1 sprayed 4 and 2 weeks before anticipated harvest was found to be insignificant in control of pre-harvest fruit drops. NAA treatment decreased flesh firmness, and did not have any significant effects on ethylene biosynthesis.

PHYSICAL, MECHANICAL AND CHEMICAL PROPERTIES OF PLUMS (cv. Santa Rosa) AFFECTED BY AMINOETHOXYVINYLGLYCINE APPLICATIONS

Background: The engineering properties (physical, mechanical and chemical) are importance to post harvest technologies of the agricultural materials. To plum fruits quality, the harvest and postharvest applications, the engineering properties of plum fruits should be considered. The effect of AVG (Aminoethoxyvinylglycine) treatments on some physical, mechanical and chemical properties of plum fruits (cv. Santa Rosa) were determined. 
 Materials and Methods: For this research, the plant material ‘Santa Rosa’ plum (Prunus domestica) fruits were obtained in Tokat/Turkey (39o51' N and 40o55' E), in 2012. AVG treatments were as 0 mg L-1, 100 mg L-1 and 200 mg L-1, and three different harvest dates including 25 July, 1 August and 7 August were used. 
 Results: The geometric mean diameter, volume of fruit and surface area values increased with AVG doses, whereas, fruit density decreased as AVG doses increased. L* and b* values decreased from 43.75 to 24.14 and 20.24 to 13.21, whereas, a* value increased from -9.03 to -2.63 for flesh plum, respectively. The fruit removal force of plum fruit increased from 19.09 N to 20.20 N in magnitude with an increase in AVG doses. The friction coefficients of fruits increased as AVG doses increased and harvest dates. Total soluble solids content was higher in AVG-0 (0 mg L-1) as compared to AVG-1 and AVG-2 (100 mg L-1 and 200 mg L-1) AVG-2 applications, whereas, pH and titratable acidity were lower in 200 mg L-1 as compared to 0 mg L-1 and 100 mg L-1 treatments. Post-harvest technological applications of the plum fruits must be designed by taking criteria into consideration for plum engineering properties.

Seed dispersal and predation of Buchenavia tomentosa Eichler (Combretaceae) in a Cerrado sensu stricto, midwest Brazil.

The ecology of seed dispersal is critical to understand the patterns of distribution and abundance of plant species. We investigated seed dispersal aspects associated with the high abundance of Buchenavia tomentosa in the Serra Azul State Park (PESA). We estimated fruit production and conducted fruit removal experiments. We carried out diurnal and nocturnal observations on frugivory as well as germination tests. Fruiting occurred in the dry season and totaled 1,365,015 ± 762,670 fruits.ha-1. B. tomentosa fruits were utilized by eight animal species. The lowland tapir (Tapirus terrestris) was considered the main seed disperser. Leafcutter ants (Atta laevigata and Atta sexdens) participated in the seed cleaning and occasionally dispersed seeds. The beetle Amblycerus insuturatus, blue-and-yellow macaw (Ara ararauna) and red-and-green macaw (Ara chloropterus) were considered pre-dispersal seed predators. The seeds manually cleaned presented higher germination rate (100%) and speed index (4.2 seeds.d-1) than that of seeds with pulp. Germination of seeds found in tapirs'feces was 40%, while for the seeds without pulp it was 25%. The high abundance of B. tomentosa in the cerrado of PESA may be due to massive fruit production, low rates of seed predation, and efficient seed dispersal by tapirs, occurring before the rains which promote germination and recruitment of this species.

Association between the concentration of n-alkanes and tolerance to cracking in commercial varieties of sweet cherry fruits

Fruit cracking is one of the major economic losses in cherry production worldwide. Factors involved in differential tolerance among varieties are unknown. This phenomenon is mainly caused by rainfall during the harvest period and is related to osmotic factors and fruit water permeability. The cuticle is a hydrophobic extracellular membrane and soluble waxes represent a mixture of aliphatic very long chain fatty acids, its derivatives and cyclic compounds like triterpenes. Analysis of waxes from enzymatic isolated sweet cherry fruit cuticles showed that the main components are triterpenes (76%), alkanes (19%) and alcohols (1%).Cracking in vitro was investigated in five sweet cherry varieties. After removal of cuticular wax fruit cracking was significantly increased. Nuclear magnetic resonance analysis (1H and 13C NMR), revealed that fruits of different sweet cherry varieties contain primarily n-alkane with 29 carbons and no iso-alkane. Gas chromatography–mass spectrometry (GC–MS) enabled identification and quantification of n-alkanes. Varieties with significantly higher concentrations of nonacosane (Kordia, Regina and Lapins) were more tolerant to cracking compared to varieties with lower amounts (Bing and Rainier).We hypothesized that there is an association between the amount of C 29 n-alkane and cracking tolerance in sweet cherry fruits. This difference could be an important factor to explain the different tolerances to cracking in fruits of sweet cherry varieties.

Variation in seed dispersal effectiveness: the redundancy of consequences in diversified tropical frugivore assemblages

Plant–frugivore mutualistic assemblages frequently combine multiple, complementary or not (i.e. redundant), distinct effects of animal species. To a large extent, the outcomes of these interactions crucially depend on the delayed consequences of frugivore effectiveness on plant recruitment. We evaluated seed dispersal effectiveness for three plant species in a Brazilian Atlantic forest with a marked habitat heterogeneity defined by bamboo and non‐bamboo patches. Twenty one, 23 and 14 bird species ate fruits ofEuterpe edulis, Sloanea guianensisandVirola bicuhybatrees, respectively. For bothEuterpeandVirola, visitation rate was the variable contributing for most variance across frugivore species in the quantitative component of effectiveness (QC, which depends on the combined effects of interaction frequency and per‐interaction effect), while the number of fruits manipulated/visit had the greatest contribution inSloanea. By combining observational data and experimental seed addition forEuterpewe tested for consistent functional patterns among species in the frugivore assemblage, extending beyond the fruit removal stage. Rankings of QC acrossEuterpefrugivores remained consistent with their relative contributions to fruit removal and, importantly, with their contributions to seedling establishment. Yet, QC of effectiveness acrossEuterpefrugivores were more homogeneous at the fruit removal and dispersal stages (contribution to seed dispersal) than for the delayed, dissemination and post‐dispersal effects on recruitment. High complementarity of diversified frugivore assemblages may increase through added variance in their delayed effects related to qualitative components of effectiveness. Our results underscore the importance of assessing how dispersal services provided by mutualistic frugivores play complementary, rather than redundant, roles in seed dispersal within heterogeneous landscapes. Such ecological outcomes highlight the value of combining observational and experimental field designs to assess functional diversity patterns of tropical frugivore assemblages and delayed effects of their interactions with plants.

Bird fruit consumption results from the interaction between fruit-handling behaviour and fruit crop size

Bird foraging behaviour is a major factor involved in mutualistic interactions of fleshy-fruited plants. Despite much research, we still lack quantified demonstrations of how fruit display traits affect fruit removal behaviour. Although the fruit crop size hypothesis proposes a general mechanism for fruit trait selection, it overlooks the fact that distinctive bird behaviours in a bird assemblage would have different effects on fruit crop size. Here, we show that the relevance of fruit crop size for bird fruit consumption is driven by two basic components of fruit foraging behaviour: fruit handling and residence time. We assessed bird fruit-eating behaviour (fruit consumption, fruit handling and residence time) and its relationship with fruit crop size, taking into account body size and spatial focal context (conspecific neighbour density and distance to the forest edge from individual plants) in a population of Vassobia breviflora (Solanaceae) in Tucumán, Argentina. At the assemblage level, fruit consumption was positively related to fruit crop size and residence time, and the interaction between fruit crop size and residence time depended on fruit-handling behaviour. At the functional group level, both gulpers and pulp consumers showed a positive relationship between fruit consumption and residence time. However, gulpers showed a negative interaction between fruit crop size and residence time, while pulp consumers showed no interaction. At the species level, fruit consumption by Turdus rufiventris (gulper) was positively related to fruit crop size, whereas fruit consumption by Thraupis sayaca and Zonotrichia capensis (pulp consumers) depended positively on residence time. Essentially, gulpers spent short residence times in plants with larger fruit crops, whereas pulp consumers spent long residence times in plants regardless of fruit crop size. The segregation between fruit-eating behaviours and their relationship with fruit crop size suggests that bird functional groups (i.e. gulpers and pulp consumers) would shape fruit display traits with different intensities.

Optimal control of anthracnose using mixed strategies

In this paper we propose and study a spatial diffusion model for the control of anthracnose disease in a bounded domain. The model is a generalization of the one previously developed in [15]. We use the model to simulate two different types of control strategies against anthracnose disease. Strategies that employ chemical fungicides are modeled using a continuous control function; while strategies that rely on cultivational practices (such as pruning and removal of mummified fruits) are modeled with a control function which is discrete in time (though not in space). For comparative purposes, we perform our analyses for a spatially-averaged model as well as the space-dependent diffusion model. Under weak smoothness conditions on parameters we demonstrate the well-posedness of both models by verifying existence and uniqueness of the solution for the growth inhibition rate for given initial conditions. We also show that the set [0, 1] is positively invariant. We first study control by impulsive strategies, then analyze the simultaneous use of mixed continuous and pulse strategies. In each case we specify a cost functional to be minimized, and we demonstrate the existence of optimal control strategies. In the case of pulse-only strategies, we provide explicit algorithms for finding the optimal control strategies for both the spatially-averaged model and the space-dependent model. We verify the algorithms for both models via simulation, and discuss properties of the optimal solutions.

Meta-analysis of anthropogenic habitat disturbance effects on animal-mediated seed dispersal.

Anthropogenic habitat disturbance is a strong biodiversity change driver that compromises not only the species persistence but also the ecological interactions in which they are involved. Even though seed dispersal is a key interaction involved in the recruitment of many tree species and in consequence critical for biodiversity maintenance, studies assessing the effect of different anthropogenic disturbance drivers on this interaction have not been performed under a meta-analytical framework. We assessed the way habitat fragmentation and degradation processes affect species diversity (abundance and species richness) and interaction rates (i.e., fruit removal and visitation rates) of different groups of seed-disperser species at a global scale. We obtained 163 case studies from 37 articles. Results indicate that habitat degradation had a negative effect on seed-disperser animal diversity, whereas habitat fragmentation had a negative effect on interaction rates. Birds and insects were more sensitive in terms of their diversity, whereas mammals showed a negative effect on interaction rates. Regarding habitat, both fragmentation and degradation had a negative effect on seed-disperser animal diversity only in temperate habitats, and negative effects on interaction rates in tropical and temperate habitats. Our results indicate that the impact of human disturbance on seed-disperser species and interactions is not homogeneous. On the contrary, the magnitude of effects seems to be dependent on the type of disturbance, taxonomic group under assessment, and geographical region where the human impact occurs.

Native Seed Dispersers May Promote the Spread of the Invasive Japanese Raisin Tree (Hovenia Dulcis Thunb.) in Seasonal Deciduous Forest in Southern Brazil

Hovenia dulcis (the Japanese raisin tree) is an invasive tree in seasonal deciduous forest in Southern Brazil. The species has an uncommon infructescence morphology, with dry fruits attached to fleshy peduncles that attract animals. This study assesses the interaction between the raisin tree and frugivore animals in seasonal deciduous forest and identifies potential dispersal relationships. Local fauna consumers and dispersers of the raisin tree were recorded by camera traps and by focal observation. Fruit removal was assessed by experiments that excluded certain animal groups while allowing access by others. We assessed seed dispersal by endozoochory by collecting the feces of birds and mammals found in the study area. The seeds found in the animal feces were then subjected to germination tests. A sampling effort of 2,305 traps/day was taken during the fructification period of the raisin tree. As a result, 28 species (16 birds and 12 mammals) were recorded from pictures taken by camera traps, and two more bird species were recorded via focal observation, for a total of 30 recorded species. Intact seeds of the raisin tree were found in the feces of Cerdocyon thous (crab-eating fox). No difference was found in seed germination between seeds obtained from fecal samples and the control. Ants can also be secondary dispersers of the raisin tree based on two observations made during the research field trips. The results obtained from this study suggest the raisin tree has different dispersal mechanisms with which different native dispersal agents are associated. Mid-size mammals, such as the crab-eating fox, are secondary dispersers by endozoochory, while birds are primary dispersers by sinzoochory.

Bicolored display of Miconia albicans fruits: Evaluating visual and physiological functions of fruit colors.

Most bird-dispersed fruits are green when unripe and become colored and conspicuous when ripe, signaling that fruits are ready to be consumed and dispersed. The color pattern for fruits of Miconia albicans (Melastomataceae), however, is the opposite, with reddish unripe and green ripe fruits. We (1) verified the maintenance over time of its bicolored display, (2) tested the communicative function of unripe fruits, (3) tested the photoprotective role of anthocyanins in unripe fruits, and (4) verified whether green ripe fruits can assimilate carbon. Using a paired experiment, we tested whether detection of ripe fruits was higher on infructescences with unripe and ripe fruits compared with infructescences with only ripe fruits. We also measured and compared gas exchange, chlorophyll a fluorescence, and heat dissipation of covered (to prevent anthocyanin synthesis) and uncovered ripe and unripe fruits. Although the bicolored display was maintained over time, unripe fruits had no influence on bird detection and removal of ripe fruits. Ripe and unripe fruits did not assimilate CO2, but they respired instead. Since the communicative function of unripe fruits was not confirmed, seed dispersers are unlikely to select the display with bicolored fruits. Because of the absence of photosynthetic activity in ripe and unripe fruits and enhanced photoprotective mechanisms in ripe fruits rather than in unripe fruits, we could not confirm the photoprotective role of anthocyanins in unripe fruits. As an alternative hypothesis, we suggest that the bicolored fruit display could be an adaptation to diversify seed dispersal vectors instead of restricting dispersal to birds and that anthocyanins in unripe fruits may have a defense role against pathogens.

All frugivores are not equal: exploitation competition determines seed survival and germination in a fleshy-fruited forest herb

Multiple-frugivore systems are common in deciduous forest communities, but multiple dispersal has rarely been examined from the perspective of plant fitness. We compare the consequences of fruit consumption by two co-occurring vertebrate frugivores (Odocoileus virginianus, white-tailed deer, and Procyon lotor, raccoon) for a fleshy-fruited forest herb (Podophyllum peltatum, mayapple). Shoot emergence, flowering, and fruit removal were monitored in natural populations in southeastern Ohio, USA. Survival of ingestion was tested in feeding trials. Germinability of ingested and non-ingested seeds was tested by experimental planting. Only 2.6 % of mayapple shoots flowered. All flowers appeared to initiate fruit, but 66 % aborted after 1–2 weeks. Of the fruits remaining, 82 % were removed unripe, evidently by deer. Only 5.5 % of fruit survived to ripen in mid-July at which time all were quickly removed. In feeding trials, 28 % of seeds survived ingestion by raccoons but only ca. 1 % survived ingestion by deer. Seeds hand harvested from unripe fruits had a lower proportion germinating in the following spring than those taken from ripe fruits as a result of significantly lower over-winter seed survival. Seeds ingested by raccoons showed significantly higher germination than non-ingested seeds and were more likely to be taken by secondary dispersers. It appears raccoons have the capacity to disperse a large proportion of mayapple seeds, whereas deer are primarily seed predators. By removing unripe fruit in early summer, deer are preempting late-summer consumption by raccoons thereby reducing the net fitness benefit to the forest herb. Frugivore service appears to be additive, potentially reducing herb fitness in proportion to consumption by the inferior dispersal agent.

Evaluation of Multipass Mechanical Harvesting on ‘Skeena’ Sweet Cherries Trained to Y-trellis

A study on multipass harvesting using a mechanical harvesting prototype was proposed for mechanical harvesting of fresh market sweet cherries. Fruit damage rate, fruit removal rate, and fruit maturity level were three of the measures used to compare the performance of the multipass harvesting method against single-pass harvesting. The multipass harvesting was conducted in four consecutive days with short duration of 2.5 seconds at each day, while the single-pass harvesting was one-time harvesting with long duration of 10 seconds at a single day. To generate baseline information for comparison, single-pass harvestings were performed on the first and the last days of the multipass harvesting. Fruit maturity level was determined by comparing the fruit skin color against a standard color chart with seven color levels. Field test results showed that the percentage of under-mature fruit (maturity levels ≤ 5) was substantially lower with multipass harvesting than that with day 1 single-pass harvesting. Similarly, the percentage of over-mature fruit (maturity level 7) was noticeably lower with multipass harvesting than that with day 4 single-pass harvesting. Multipass harvesting achieved a fruit removal rate of 83.4% ± 10.3% and a harvest-induced fruit damage rate of 5.0% ± 4.4%. The corresponding fruit removal rates from single-pass harvesting tests were 48.0% ± 16.1% on day 1 and 66.7% ± 16.2% day 4. Harvest-induced fruit damage rates with single-pass harvesting were 20.1% ± 9.9% on day 1 and 11.8% ± 6.0% on day 4. The results supported the hypothesis that multipass of short-duration shaking offer a potential to achieve a higher overall harvesting efficiency with better fruit quality, and therefore could lead to an optimal solution for mechanical harvesting of fresh market sweet cherries. It is noted that comprehensive economic analysis will be necessary to establish commercial viability of the system in comparison with single-pass solutions.

The Asian elephant is amongst the top three frugivores of two tree species with easily edible fruit

Abstract:Large animal species are prone to local extirpation, but ecologists cannot yet predict how the loss of megaherbivores affects ecosystem processes such as seed dispersal. Few studies have compared the quantity and quality of seed dispersal by megaherbivores versus alternative frugivores in the wild, particularly for plant species with fruit easily consumed by many frugivorous species. In a disturbed tropical moist forest in India, we examine whether megaherbivores are a major frugivore of two tree species with easily edible, mammal-dispersed fruit. We quantify the relative fruit removal rates of Artocarpus chaplasha and Careya arborea, by the Asian elephant (Elephas maximus) and alternative dispersers. Through focal watches and camera trapping, we found the elephant to be amongst the top three frugivores for each tree species. Furthermore, seed transects under A. chaplasha show that arboreal frugivores discard seeds only a short distance from the parental tree, underscoring the elephant's role as a long-distance disperser. Our data provide unprecedented support for an old notion: megaherbivores may be key dispersers for a broad set of mammal-dispersed fruiting species, and not just fruit inaccessible to smaller frugivores. As such, the elephant may be particularly important for the functional ecology of the disturbed forests it still inhabits across tropical Asia.

Scatter-hoarding rodents disperse seeds to safe sites in a fire-prone ecosystem

Fire can potentially decimate soil seed banks, even for species that are abundant in fire-prone areas. Many plants, like the widespread and dominant members of the genus Arctostaphylos in the fire-prone California Floristic Province, have seeds that (i) have no clear adaptions for dispersal and (ii) experience lethal fire temperatures if present on or near the soil surface. In this study, we aim to resolve these juxtaposed observations by mechanistically determining how one species, Arctostaphylos patula, is dispersed. To distinguish among dispersal modalities and determine the seed shadow, deposition patterns, and the conditions under which seeds germinate, we employed full-shrub exclosure treatments to monitor fruit removal, used a mark-relocation technique by radioactively labeling seeds, identified dispersers using motion-sensor cameras, and surveyed seedlings following fire to relate natural germination patterns to measured patterns from our experiment. Seed removal from exclosure treatments that allowed rodents access to shrubs was higher than those that prevented rodent access to shrubs, and cameras at radioactively labeled-seed stations failed to detect the presence of any other disperser; thus implicating rodents as the primary disperser of A. patula seeds. This evidence is corroborated by our finding from tracking radioactively labeled seeds that the depth at which rodents bury seeds completely overlaps with the depth from which we observed seedlings germinate following two fire events. Our study extends the boundary of what is understood as a scatter-hoarding seed dispersal syndrome and identifies a mechanism that allows populations of Arctostaphylos to exist in spite of recurrent fires that can be lethal to seeds and hazardous to plant populations.

Fruit availability influences the seasonal abundance of invasive stink bugs in ornamental tree nurseries

Invasive plant-feeding insects cause billions of dollars in economics losses annually around the world. Understanding how they utilize different host plants directly informs their management. The highly invasive brown marmorated stink bug, Halyomorpha halys (Stal) (Hemiptera: Pentatomidae), has destroyed crops and invaded homes since its discovery in the U.S. in the mid-1990s. In this study, we test the hypothesis that in diverse resource environments, the presence and maturity of fruits on trees influences the abundance of H. halys. Observational surveys of the abundance of H. halys life stages (egg masses, nymphs, and adults) on 3884 trees of 223 cultivars in woody plant nurseries revealed that fruit maturity was a strong predictor of the seasonal abundance and within-tree distribution of H. halys. We next explicitly tested whether fruits themselves were the key resource for H. halys through a manipulative field experiment. Removal of fruits from trees suppressed stink bug abundance throughout the season. Despite being considered a broad feeding generalist, our results highlight that in landscapes with highly heterogeneous and ephemeral resources, H. halys specializes on finding mature fruits. Therefore, H. halys can be controlled by designing landscapes with fruitless varieties of popular trees, exploiting phenological mismatches between the pest and its host plants, and through targeted management of H. halys on fruiting trees in the landscape.

Seed predation in a human-modified tropical landscape

Abstract:Contemporary defaunation of fragmented forests potentially alters patterns of seed predation and dispersal. Alternatively, the remaining fauna may compensate for missing animals, resulting in equivalent rates of seed dispersal and predation. In the Los Tuxtlas region of southern Mexico, populations of large terrestrial fruit-eating mammals are diminished or absent from many forest remnants. This study reports fruit removal and seed predation patterns of Poulsenia armata (Moraceae), in forest fragments and a continuous forest (LTBS). Contrary to expectation, we found no differences in seed predation (mean ± SD) between LTBS (7.2 ± 1.8 seeds per station) and forest fragments (5.6 ± 1.1). However more fruits were removed in the LTBS (11.4 ± 0.9 fruits per station) than in forest fragments (8.1 ± 0.8). Animal activity, recorded by camera traps, differed between animal guild with fewer seed dispersers in forest fragments (mean = 0.43 ± 0.02 photos wk−1) than in the LTBS (mean = 0.68 ± 0.05). Fruits and seeds attracted many species of mammal (n = 12) in both habitats, indicating substantial redundancy. Remnant forest patches in the Los Tuxtlas landscape retain great ecological value, both as refuges for mammals and habitats for trees, such as P. armata.

Pre-dispersal seed removal of fleshy fruits and Quercus coccifera (Fagaceae) acorns in a recently burned Mediterranean habitat

The seed fate in early successional habitats can determine plant composition and regeneration capacity after disturbance. Predispersalseed removal has been poorly studied in Mediterranean habitats, especially in burned and logged habitats. We assessed it for two years in pine forests with experiments excluding vertebrates from fleshy fruits (infructescences of Smilax aspera and Rubia peregrina) and acorns (branches of Quercus coccifera). We compared one unburned and one burned area (control). Acorn removal was nil in the burned area while in the unburned habitat seed removal occurred from the beginning of the experiments. It is suggested that the greater vegetation cover in the unburned area shelter rodents from predators and increased their activity. In contrast, reduced cover in the burned area and the occurrence of gnawed acorns on the ground suggest acorn removalby rodents mainly in the post-dispersive stage. Smilax aspera seed removal was slower, and total loss of fruits due to senescence higher,in the burned area. Seed removal appears to be conditioned by interannualvariations related to the activity and density of granivores and frugivores, the availability of fleshy fruits, and the maturation of fruits.In post-fire managed areas the role of granivores and frugivores in the regeneration process should be taken into account.

Pre-dispersal seed removal of fleshy fruits and Quercus coccifera (Fagaceae) acorns in a recently burned Mediterranean habitat.

Pre-dispersal seed removal of fleshy fruits and Quercus coccifera (Fagaceae) acorns in a recently burned Mediterranean habitat. The seed fate in early successional habitats can determine plant composition and regeneration capacity after disturbance. Pre-dispersal seed removal has been poorly studied in Mediterranean habitats, especially in burned and logged habitats. We assessed it for two years in pine forests with experiments excluding vertebrates from fleshy fruits (infructescences of Smilax aspera and Rubia peregrina) and acorns (branches of Quercus coccifera). We compared one unburned and one burned area (control). Acorn removal was nil in the burned area while in the unburned habitat seed removal occurred from the beginning of the experiments. It is suggested that the greater vegetation cover in the unburned area shelter rodents from predators and increased their activity. In contrast, reduced cover in the burned area and the occurrence of gnawed acorns on the ground suggest acorn removal by rodents mainly in the post-dispersive stage. Smilax aspera seed removal was slower, and total loss of fruits due to senescence higher, in the burned area. Seed removal appears to be conditioned by interannual variations related to the activity and density of granivores and frugivores, the availability of fleshy fruits, and the maturation of fruits. In post-fire managed areas the role of granivores and frugivores in the regeneration process should be taken into account.

Modification and Field Evaluation of an Experimental Mechanical Sweet Cherry Harvester

Abstract. A two-unit experimental sweet cherry harvester was modified with a goal to improve its harvest performance by changing each unit’s rapid impact fruit removal mechanism to a continuous impact (shaking) mechanism. During harvest, an end effector (rapid impactor) was placed at selected actuation points on fruiting scaffold branches to transfer vibrational energy for fruit release. Removed fruit was caught by a catching system and was collected into a lug or bin placed on a platform. Remote control capability was incorporated into each harvester unit to improve its operability. This article reports details on these added features and results from field evaluation studies conducted in 2012 and 2013 harvest seasons in Washington State. Harvest performance was evaluated in terms of harvesting rate and harvest efficiency. Harvesting rate consisted of two parts: tree coverage rate (number of trees harvested per unit time) and fruit removal rate (weight of fruit removed per unit time). Harvest efficiency included fruit removal efficiency (weight of removed fruit per weight of total fruit on tree) and collection efficiency (weight of machine-caught fruit per weight of removed fruit). In the first of two tests conducted in 2012, using only the left half of the harvester to harvest the left half of trees, average fruit removal efficiency of 83% was achieved and of those removed, over 85% was collected. Tree coverage rate was on average 19 and 15 trees/h, respectively, for 10 and 15 s shaking per actuation point with fruit removal rate of 7.4 kg/min. In the second test conducted in 2012, tree coverage rate averaging 30 trees/h was achieved. It was observed in 2012 tests that a variable shaking duration would be necessary to not shake branches after most of the cherries are detached. The 2013 tests used actuation point-specific shaking periods on Ethephon-treated trees, resulting in an average tree coverage rate of 36 trees/h, removal efficiency of 87%, and collection efficiency of 79%. Harvest-induced fruit damage in 2013 tests ranged from 0% to 20% with an average of 10%, which was better or comparable to previously reported values. Use of remote control, compared to control from the operator’s seat, increased operator’s visibility of target branches up to two times and contributed to 16% less time with 9% more accuracy in positioning the continuous impactor on target branches. These results show promise for practical applicability of this harvest system in commercial operation.